cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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hweight.c (1961B)

      1// SPDX-License-Identifier: GPL-2.0
      2#include <linux/export.h>
      3#include <linux/bitops.h>
      4#include <asm/types.h>
      5
      6/**
      7 * hweightN - returns the hamming weight of a N-bit word
      8 * @x: the word to weigh
      9 *
     10 * The Hamming Weight of a number is the total number of bits set in it.
     11 */
     12
     13unsigned int __sw_hweight32(unsigned int w)
     14{
     15#ifdef CONFIG_ARCH_HAS_FAST_MULTIPLIER
     16	w -= (w >> 1) & 0x55555555;
     17	w =  (w & 0x33333333) + ((w >> 2) & 0x33333333);
     18	w =  (w + (w >> 4)) & 0x0f0f0f0f;
     19	return (w * 0x01010101) >> 24;
     20#else
     21	unsigned int res = w - ((w >> 1) & 0x55555555);
     22	res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
     23	res = (res + (res >> 4)) & 0x0F0F0F0F;
     24	res = res + (res >> 8);
     25	return (res + (res >> 16)) & 0x000000FF;
     26#endif
     27}
     28EXPORT_SYMBOL(__sw_hweight32);
     29
     30unsigned int __sw_hweight16(unsigned int w)
     31{
     32	unsigned int res = w - ((w >> 1) & 0x5555);
     33	res = (res & 0x3333) + ((res >> 2) & 0x3333);
     34	res = (res + (res >> 4)) & 0x0F0F;
     35	return (res + (res >> 8)) & 0x00FF;
     36}
     37EXPORT_SYMBOL(__sw_hweight16);
     38
     39unsigned int __sw_hweight8(unsigned int w)
     40{
     41	unsigned int res = w - ((w >> 1) & 0x55);
     42	res = (res & 0x33) + ((res >> 2) & 0x33);
     43	return (res + (res >> 4)) & 0x0F;
     44}
     45EXPORT_SYMBOL(__sw_hweight8);
     46
     47unsigned long __sw_hweight64(__u64 w)
     48{
     49#if BITS_PER_LONG == 32
     50	return __sw_hweight32((unsigned int)(w >> 32)) +
     51	       __sw_hweight32((unsigned int)w);
     52#elif BITS_PER_LONG == 64
     53#ifdef CONFIG_ARCH_HAS_FAST_MULTIPLIER
     54	w -= (w >> 1) & 0x5555555555555555ul;
     55	w =  (w & 0x3333333333333333ul) + ((w >> 2) & 0x3333333333333333ul);
     56	w =  (w + (w >> 4)) & 0x0f0f0f0f0f0f0f0ful;
     57	return (w * 0x0101010101010101ul) >> 56;
     58#else
     59	__u64 res = w - ((w >> 1) & 0x5555555555555555ul);
     60	res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
     61	res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
     62	res = res + (res >> 8);
     63	res = res + (res >> 16);
     64	return (res + (res >> 32)) & 0x00000000000000FFul;
     65#endif
     66#endif
     67}
     68EXPORT_SYMBOL(__sw_hweight64);